Field of the Invention
The invention relates to a resist pattern-forming method and a photoresist composition.
Discussion of the Background
A chemically-amplified photoresist composition is normally designed so that an acid is generated in the exposed area upon application of electromagnetic radiation (e.g., deep ultraviolet rays (e.g., ArF excimer laser light or KrF excimer laser light) or charged particle rays (e.g., electron beams)), and a difference in solubility in a developer occurs between the exposed area and the unexposed area due to the effect of the acid. A resist pattern is formed on a substrate utilizing the above phenomenon.
A photoresist composition that includes an acid generator that generates an acid upon application of exposure light, and a polymer that includes an acid-labile group has been normally used so that a difference in solubility in a developer occurs between the exposed area and the unexposed area. When such a photoresist composition is used, an acid generated by the acid generator serves as a catalyst, and the acid-labile group dissociates to produce a carboxyl group or the like. As a result, the solubility of the polymer in the developer (e.g., alkaline aqueous solution or an organic solvent) changes, and dissolution contrast occurs between the exposed area and the unexposed area, so that a resist pattern that exhibits excellent lithographic properties can be formed (see Japanese Patent Application Publication (KOKAI) No. 59-45439 and Japanese Patent Application Publication (KOKAI) No. 2000-199953).
In recent years, it has been desired to form a finer pattern in higher yield. In particular, an improvement in exposure latitude (EL) performance, mask error enhancement factor (MEEF) performance, and resolution of the resist pattern has been desired.